AUSTIN, Texas – The term "returning starters" is a bit of misnomer around here.

Texas returns six defensive players who started in the 26-24 Alamo Bowl victory over Iowa that ended the 2006 season.

But will they all be starting the Sept. 1 season opener against Arkansas State? That remains up in the air.

Texas began spring practice by warning its players that almost no job is safe. That's particularly true for a defense that ranked 99th in the nation against the pass last season.

"It could cause complacency if a guy thinks, 'I'm going to get to play just because I'm going to get to play,' '' Texas coach Mack Brown said. "We tell them in that rotation of two-deep that if you're not playing your part, then you'll lose plays. And if you're not doing it to the level that you should, then you could not play at all."

Consider this a season of transition for the Texas defense.

A team that has produced the last two Thorpe Award winners – Michael Huff in 2005 and Aaron Ross last season – returns only one starter in the secondary. Brian Robison and Tim Crowder have left the defensive line after combining for 26 sacks the last two seasons.

Texas also had to make changes on its staff when co-defensive coordinator Gene Chizik accepted Iowa State's head coaching job.

All those departures haven't reduced the Longhorns' optimism.

The loss of Chizik allowed Texas to reunite Duane Akina and Larry MacDuff, who coached together on the famous Arizona "Desert Swarm" defenses of the early 1990s.

Akina will call defensive signals at Texas for the first time after serving as co-defensive coordinator the last three years. Mac Duff is a 36-year coaching veteran who left a job on the San Francisco 49ers' staff to take over as the Longhorns' linebackers coach.

"He's very tough and demanding," Brown said of Mac Duff, "and he might be the most organized human being I've ever seen."

Most of Texas' current players were in elementary school when Arizona's Desert Swarm ranked among the nation's top defenses in most statistical categories from 1990 to 1995. But they've been around Akina and Mac Duff long enough to know what Texas fans can expect this fall.

The emergence of Muckelroy and other talented underclassmen give Texas fans more cause for hope, while giving incumbent starters reason to worry.

Muckelroy already has developed a reputation as one of the Longhorns' hardest hitters despite missing most of last season with a ruptured tendon in his right ring finger. The Longhorns also expect a big year from former five-star prospect Sergio Kindle, who struggled with an ankle injury last fall after entering college as the nation's top linebacker recruit.

Those two sophomores could be good enough to crack the lineup, even though Texas returns all three of last year's starting linebackers: Rashad Bobino, Scott Derry and Robert Killebrew. The underclassmen love the fact that the coaches are basically working without a depth chart.

"For the young players, it's an opportunity for us to get our chance," Muckelroy said. "Having no depth chart is good for everyone. It's going to make everyone work harder and get that much better."

"We're looking for guys who will play defense and be responsible,'' Akina said. "We're looking for great athletes, but (being) a great athlete doesn't equate to being a great football player. We're looking for guys who will play the right defense structurally. We're looking for guys who will play with great effort. Run to the football. And when you get there, (you have to) strike.

"I'm probably a little more over the top than most in that I refuse to be associated with a defensive secondary that is considered soft. If we do anything, we'll strike.''

Akina's main challenge is to shore up a pass defense that gave up too many big plays last season despite having two probable first-day draft picks – Ross and Michael Griffin – in the secondary.

Ohio State and Kansas State combined for 13 pass completions of at least 20 yards in their victories over Texas last season. The Longhorns gave up six touchdown passes and recorded only one interception in those two games.

"We'd give up three to five big plays a game in certain games that would hurt us," Kelson said. "We'd play 70 plays, and 65 of them would be perfect. Those other five plays were the ones that would hurt us the most. We just need to eliminate those few plays that hurt us."

Texas coaches admitted that they focused most of their attention last year on stopping the run. The Longhorns allowed just 2.3 yards per carry and boasted the nation's third-ranked run defense (behind only Michigan and Texas Christian), but opposing teams adjusted by moving the ball through the air.

Kansas State won a 45-42 shootout with Texas despite rushing for only 23 yards on 25 carries. In a play that perhaps best illustrated the Longhorns' futility against the pass, Ross was left on an island to try to cover Ted Ginn Jr., who blazed past him for a 29-yard touchdown catch late in the first half of Ohio State's 24-7 victory at Texas.

"We've gone back and looked at every one of our big plays, and we could have done better than we did," Brown said. "It wasn't all just scheme. We put ourselves out there some, but we should probably do a better job in understanding what (situation) we're in (when we're) against someone who can blister you so easily and not put an Aaron Ross out there against Ted Ginn or put an Aaron Ross out there every game by himself.''

And it's even more of a concern now that the Longhorns don't have Ross – or perhaps anyone of his caliber – in their secondary. How do they protect their inexperienced defensive backs while remaining as tough as ever against the run?

That's the dilemma Akina and Co. face as they try to retool the defense. The Alamo Bowl probably offered a preview of how the Longhorns might look this fall.

The Longhorns allowed Iowa's Drew Tate to pass for 274 yards and a pair of touchdowns in that game, but they also recorded three sacks.

"We'll have opportunities to come after the quarterback a little bit," Akina said. "We'll still have to stop the run. That was the stress of last year. That's what we were going to do. We built things on stopping the run. We're going to do that, and we'll get back to some of those things that had helped us be a real good coverage team, too. Hopefully we'll blend those two concepts together."

But the changes surrounding Texas' defense aren't restricted to the scheme and staff. The departures of Ross, Crowder and Michael Griffin leave Texas struggling to replace three of last year's Rivals.com All-America selections.

That doesn't seem to bother the Longhorns, who believe plenty of lesser-known players are ready to make the leap to stardom. After all, Texas has signed three five-star defensive players and 11 four-star defensive prospects the last two years.

"Everybody thinks about the starters," Muckelroy said, "but you just know the backups were just as good here at Texas."